pcat: separate MBR code and OS code

MBR code now strictly loads OS code into memory and jumps into it.

Now, I've got to consolidate my assembler code, modrm logic is
messed up.

blk/753

@@ -4,6 +4,7 @@
 : INT, 0xcd A, A, ;
 ( no argument, flow ops are special )
 : JMP8, 0xeb A, ; : JMP16, 0xe9 A, ; : JZ, 0x74 A, ;
+: JMPr, 0xff A, 7 AND 0xe0 OR A, ;
 : LODSB, 0xac A, ; : CLI, 0xfa A, ; : HLT, 0xf4 A, ;
 : STI, 0xfb A, ;
 : ORrr, 0x08 A, MODRMrr A, ;

blk/811

@@ -2,14 +2,9 @@ H@ ORG ! 0x7c00 BIN( ! ( BIOS loads boot bin at 0x7c00 )
 JMP8, L1 FWR8 ( start )
 ORG @ 0x25 + HERE ! ( bypass BPB )
 L1 FSET ( start )
-CLI, CLD, AX AX XORxx, DS AX MOVsx, ES AX MOVsx, STI,
+CLI, CLD, AX AX XORxx, DS AX MOVsx, ES AX MOVsx,
+SS AX MOVsx, SP 0xffff MOVrI, STI,
 AH 2 MOVri, DX 0 MOVrI, CH 0 MOVri, CL 2 MOVri, AL 1 MOVri,
 BX 0x8000 MOVrI, 0x13 INT, ( read 2nd sector of boot floppy )
-SI 0x8000 MOVrI, AH 0x0e MOVri, ( print char )
-L1 BSET ( loop ) LODSB, AL AL ORrr, ( end of str? )
-JZ, L2 FWR8 ( next ) 0x10 INT, ( print char )
-JMP8, L1 ( loop ) BWR
-L2 FSET ( next ) AH 0 MOVri, 0x16 INT, ( read kbd )
-AH 0x0e MOVri, 0x10 INT, ( spit read char ) HLT, ( done )
+BX JMPr,
 ORG @ 0x1fe + HERE ! 0x55 A, 0xaa A,
-," Hello from 2nd sector of boot floppy!" 0 A,

blk/812

@@ -0,0 +1,10 @@
+H@ ORG ! 0x8000 BIN( !
+JMP8, L1 FWR8 ( start )
+L2 ( msg ) BSET ," Hello World!" 0 A,
+L1 FSET ( start )
+SI L2 @ ( msg ) MOVrI, AH 0x0e MOVri, ( print char )
+L1 BSET ( loop ) LODSB, AL AL ORrr, ( end of str? )
+JZ, L2 FWR8 ( next ) 0x10 INT, ( print char )
+JMP8, L1 ( loop ) BWR
+L2 FSET ( next ) AH 0 MOVri, 0x16 INT, ( read kbd )
+AH 0x0e MOVri, 0x10 INT, ( spit read char ) HLT, ( done )

recipes/pcat/Makefile

@@ -1,16 +1,26 @@
-TARGET = boot.bin
+TARGET = disk.bin
 BASEDIR = ../..
 EDIR = $(BASEDIR)/emul
 STAGE = $(EDIR)/stage
 
 .PHONY: all
 all: $(TARGET) 
-$(TARGET): xcomp.fs $(STAGE)
+mbr.bin: mbr.fs $(STAGE)
+	cat mbr.fs | $(STAGE) > $@
+
+os.bin: xcomp.fs $(STAGE)
 	cat xcomp.fs | $(STAGE) > $@
 
+disk.bin: mbr.bin os.bin
+	cat mbr.bin os.bin > $@
+
 $(STAGE):
 	$(MAKE) -C $(EDIR) stage
 
 .PHONY: emul
 emul: $(TARGET)
 	qemu-system-i386 -fda $(TARGET)
+
+.PHONY: clean
+clean:
+	rm *.bin

recipes/pcat/mbr.fs

@@ -0,0 +1,4 @@
+750 LOAD
+811 LOAD
+ORG @ 256 /MOD 2 PC! 2 PC!
+H@ 256 /MOD 2 PC! 2 PC!

recipes/pcat/xcomp.fs

@@ -1,4 +1,4 @@
 750 LOAD
-811 LOAD
+812 LOAD
 ORG @ 256 /MOD 2 PC! 2 PC!
 H@ 256 /MOD 2 PC! 2 PC!